WO2001069066A1

WO2001069066A1 - Method for operating a multi-cylinder internal combustion engine

Info

Publication number: WO2001069066A1
Application number: PCT/DE2001/000346
Authority: WO
Inventors: Martin Klenk; Stephan Uhl
Original assignee: Robert Bosch Gmbh
Priority date: 2000-03-11
Filing date: 2001-01-30
Publication date: 2001-09-20
Also published as: BR0105031B1; CN1364216A; MXPA01011465A; AU3914501A; CN1364216B; EP1179130A1; BR0105031A; DE10012025A1; DE50101962D1; JP2003527527A; EP1179130B1; DE10190969D2; RU2260141C2

Abstract

The invention relates to a method for operating a multi-cylinder internal combustion engine (1), especially a direct injection internal combustion engine. According to the invention, fuel is injected into a combustion chamber (4) via a high-pressure injection valve (9) in a first operational mode during a compression phase and in a second operational mode during an induction phase. In addition, the engine is switched over between the operational modes, and the torques of the individual cylinders of the internal combustion engine are equated, whereby the cylinder equalization is effected in the first operational mode by means of a controller. In order to be able to effect the cylinder equalization in a simple, quick and effective manner and while using few calculations, the invention provides that the injection correction factors (r_ik) for correcting cylinder-specific torque errors (M_f_ik) in a number of operating points (k) are determined and stored, statistical flow rate errors (q_stat) and dynamic flow rate errors (q_dyn) of the high-pressure injection valve (9) are determined, and the quantity of fuel to be injected into the combustion chamber (4) is corrected for according to the determined flow rate errors (q_stat, q_dyn) of the high-pressure injection valve (9).

Description

Method for operating a multi-cylinder internal combustion engine

State of the art

The present invention relates to a method for operating a multi-cylinder internal combustion engine, in particular a direct-injection internal combustion engine, in which fuel is injected into a combustion chamber via a high-pressure injection valve in a first operating mode during a compression phase and in a second operating mode, and in which between the Operating modes switched and the torques of the individual cylinders of the internal combustion engine are equated, the cylinder equation in the first

Operating mode is carried out by means of a controller. In addition, the present invention relates to an internal combustion engine, in particular a direct-injection internal combustion engine, with a combustion chamber into which fuel can be injected in a first operating mode during a compression phase and in a second operating mode during an intake phase via a high-pressure injection valve, with a control device for switching between the operating modes and with a controller for cylinder equalization at least in the first operating mode. Finally, the present invention also relates to a control device for such an internal combustion engine. Systems of this type for the direct injection of fuel into the combustion chamber of an internal combustion engine are generally known. A distinction is made between a so-called stratified operation as the first operating mode and a so-called homogeneous operation as the second operating mode. Stratified operation is used in particular for smaller loads, while homogeneous operation is used for larger loads applied to the internal combustion engine.

In shift operation, the fuel is used during the

Compression phase of the internal combustion engine is injected into the combustion chamber in such a way that a fuel cloud is in the immediate vicinity of a spark plug at the time of ignition. This injection can take place in different ways. It is thus possible that the injected fuel cloud is already at the spark plug during or immediately after the injection and is ignited by the latter. It is also possible that the injected fuel cloud is guided to the spark plug by a charge movement and only then ignited. In both combustion processes, there is no uniform fuel distribution, but a stratified charge.

The advantage of shift operation is that the applied smaller loads can be carried out by the internal combustion engine with a very small amount of fuel. However, larger loads cannot be met by shift operation.

In the homogeneous operation intended for such larger loads, the fuel is injected during the intake phase of the internal combustion engine, so that swirling and thus distribution of the fuel in the combustion chamber can still take place without any problems. In this respect, the homogeneous operation corresponds approximately to the mode of operation of Yd HH in ooom

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Compensating high-pressure injection valves are known from DE 198 28 279 means for synchronizing cylinders of a multi-cylinder internal combustion engine. The torques of the individual cylinders are

Internal combustion engine equivalent by varying the amount of fuel to be injected into the combustion chamber. A torque delivery of the individual cylinders that is as uniform as possible has a positive effect on the smooth running, the emission and the consumption of the internal combustion engine.

In DE 198 28 279 AI it is proposed to assign a pilot control map to each cylinder, which is determined adaptively during the operation of the internal combustion engine. In shift operation, the cylinders are equalized by a controller, and the pilot control map can be used to relieve the controller for cylinder equalization and to improve dynamics. In homogeneous operation, an injection correction factor determined from the pilot control map is used to correct the

Injection time used. The output variable of the controller is constant over time in homogeneous operation, i. H. the controller is inactive and cylinder equalization is controlled.

In DE 198 28 279 AI, the controlled cylinder equalization takes place in homogeneous operation only taking into account the static flow rate error, i. H. only long injection times are evaluated. The dynamic

Flow rate errors are not taken into account. Thereby the torque errors of the individual cylinders can be corrected for long injection times, ie if the internal combustion engine has to generate a large torque and is operated under load. With short injection times, e.g. B. when the engine is idling, can

However, torque errors are not adequately compensated for and the internal combustion engine runs erratically and unevenly.

It is the object of the present invention that

To improve cylinder equalization in such a way that it can correct the torque errors of the individual cylinders both with large and with short injection times and in both the first operating mode and the second operating mode of the internal combustion engine.

To achieve this object, the invention proposes, starting from the method of the type mentioned at the outset, that injection correction factors necessary for correcting torque errors of the individual cylinders are determined and stored in a plurality of operating points, that static flow rate errors and dynamic flow rate errors of the high-pressure injection valve are determined from the injection correction factors and that in the amount of fuel to be injected into the combustion chamber is corrected as a function of the determined flow rate errors of the high-pressure injection valve.

Advantages of the invention

According to the invention, the injection correction factors for the individual cylinders are therefore first

Internal combustion engine recorded in several operating points. On

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According to a preferred embodiment of the present invention, it is proposed that the injection time of the high-pressure injection valves be varied in order to correct the amount of fuel to be injected into the combustion chamber. The two quantities of correction determined for each cylinder of the internal combustion engine - the static and the dynamic flow rate error - are then used to correct the amount of fuel to be injected via the corresponding high-pressure injection valve. With the static flow rate error each injection time is multiplied and with the dynamic flow rate error aditively.

The ascertained are advantageously

Injection correction factors for cylinder equalization are stored in a map. The map is preferably stored in the control unit of the internal combustion engine. The map is spanned on the one hand by the speed of the internal combustion engine and on the other hand by the torque given off by the internal combustion engine. During operation of the internal combustion engine, the control unit can then access the stored injection correction factors, determine the corresponding flow rate errors of the high-pressure injection valve and correct the amount of fuel to be injected into the combustion chamber accordingly.

According to a preferred embodiment of the present invention, it is proposed that for long injection times the injection correction factor corresponding to the operating point is used as a static flow rate error. The

Injection correction factor provides larger ones Injection times a reliable value for the static flow rate error, since the influence of the dynamic error, ie the error due to the opening and closing process, the smaller the high pressure injector, the longer the injection times.

Likewise, according to another preferred

Embodiment of the present invention proposed that, with short injection times, the injection correction factor corresponding to the operating point is more dynamic

Flow rate error is used. The shorter the injection times, i. H. the shorter the period in which the high-pressure injector is opened or closed, the greater the influence of the dynamic error on the flow rate error of the high-pressure injector.

The present invention enables the manufacturing tolerances of high-pressure injection valves to be expanded. This becomes possible because of the behavior of everyone

High pressure injector is recorded individually for the cylinder and is taken into account in the cylinder equalization. In addition, the dynamic flow rate errors of the high-pressure injection valves are also taken into account in the cylinder equalization, whereby a complete correction of the torque errors of the individual cylinders is possible, in particular with short injection times.

Of particular importance is the implementation of the method according to the invention in the form of a control element which is provided for a control unit of an internal combustion engine, in particular a direct-injection internal combustion engine. In this case, a program is stored on the control element, which program on a computing device, in particular on a microprocessor Control unit is executable and suitable for executing the method according to the invention. In this case, the invention is thus implemented by a program stored on the control element, so that the control element provided with the program does the same in the same way

Invention represents like the method, for the execution of which the program is suitable. In particular, an electrical storage medium can be used as the control element, for example a read-only memory (ROM) or a flash memory.

As a further solution to the problem of the present invention, it is proposed, starting from the internal combustion engine of the type mentioned at the outset, that the control unit determines and stores injection correction factors necessary for correcting torque errors of the individual cylinders in a plurality of operating points, from the injection correction factors a static flow rate error and a dynamic flow rate error of the high-pressure injection valve is determined and the amount of fuel to be injected into the combustion chamber is corrected as a function of the determined flow rate narrow errors of the high-pressure injection valve.

Finally, as a solution to the object of the present invention, starting from the control device for an internal combustion engine of the type mentioned at the outset, it is proposed that the control device for correcting torque errors of the individual cylinders ascertains and stores necessary injection correction factors in a plurality of operating points, a static flow rate error and one from the injection correction factors dynamic

Flow rate error of the high pressure injector determined and the amount of fuel to be injected into the combustion chamber depending on the determined

Flow rate errors of the high pressure injector corrected.

The controller interventions of a controller for cylinder equalization are preferably used as injection correction factors.

drawings

A preferred embodiment of the present invention is explained in more detail below with reference to the drawings. Show it:

Figure 1 is a schematic block diagram of an internal combustion engine according to the invention according to a preferred embodiment;

FIG. 2 shows a further schematic block diagram of the internal combustion engine from FIG. 1; and

Figure 3 shows an inventive control device according to a preferred embodiment.

Description of the embodiments

FIG. 1 shows a direct-injection internal combustion engine 1 of a motor vehicle, in which a piston 2 can be moved back and forth in a cylinder 3. The internal combustion engine 1 has z cylinders 3. The cylinders 3 are each provided with a combustion chamber 4, which is delimited, among other things, by the piston 2, an inlet valve 5 and an outlet valve 6. An intake pipe 7 is coupled to the inlet valve 5 and an exhaust pipe 8 is coupled to the outlet valve 6.

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The corrected injection time t_ik for a specific cylinder i at a specific operating point k is then determined in a processing unit 21 of the control unit 15 from the injection correction factors r_ik of the individual cylinders i. More precisely, each calculated injection time is corrected multiplicatively with the static flow rate error g_stat, and each injection time is aditively corrected with the dynamic flow rate error ej_dyn. In addition, the processing unit 21 can also filter or normalize the determined injection times t_ik.

In summary, the injection correction factors r_ik are first determined. In shift operation and in homogeneous operation up to lambda = 0.85, the torque errors M_f_ik are regulated to zero by means of the controller R_i. The controller interventions of the controller R_i correspond to the injection correction factors r_ik. In stratified operation there is a proportional between fuel quantity and applied torque M_k and in homogeneous operation up to lambda = 0.85 a non-linear one

Context. The injection correction factors r_ik are stored in the cylinder-specific characteristic maps K_i in the control unit 15.

During the operation of the internal combustion engine 1, K i are used for a specific value in the characteristic maps

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Claims

Expectations

l. Method for operating a multi-cylinder internal combustion engine (1), in particular a direct-injection internal combustion engine, in which fuel is injected into a combustion chamber (4) via a high-pressure injection valve (9) in a first operating mode during a compression phase and in a second operating mode, and at which is switched between the operating modes and the torques of the individual cylinders of the internal combustion engine are assimilated, the cylinder equalization in the first operating mode being carried out by means of a controller, characterized in that injection correction factors (i) necessary for correcting torque errors (M_f_ik) of the individual cylinders (i) r_ik) are determined and stored in several operating points (k) from the injection correction factors (r_ik) static flow rate errors (q_stat) and dynamic flow rate errors (q_dyn) of the

High pressure injection valve (9) are determined and - the injected into the combustion chamber (4)

The amount of fuel is corrected as a function of the determined flow rate errors (q_stat, q_dyn) of the high-pressure injection valve (9).

2. The method according to claim 1, characterized in that the injection correction factors (r_ik) only during the first operating mode.

3. The method according to claim 1, characterized in that the injection correction factors (r_ik) are detected both in the first operating mode and in the second operating mode.

4. The method according to claim 3, characterized in that from the injection correction factors (r_ik) detected in the first operating mode and from the injection correction factors (r_ik) detected in the second operating mode, common static and dynamic flow rate errors (q_stat, q_dyn) are determined and the correction of the in fuel quantity to be injected into the combustion chamber (4).

5. The method according to any one of claims 1 to 4, characterized in that as the injection correction factors (r_ik), the controller interventions required to correct the torque errors (M_f_ik) of the individual cylinders (i)

Regulator can be used for cylinder equalization.

6. The method according to any one of claims 1 to 5, characterized in that the injection time is varied to correct the amount of fuel to be injected into the combustion chamber (4).

7. The method according to any one of claims 1 to 6, characterized in that the injection correction factors (r_ik) are stored in a map (K_i).

8. The method according to any one of claims 1 to 7, characterized in that for long injection times the injection correction factor (r_ik) corresponding to the operating point (k) is used as a static flow rate error (g_stat).

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High pressure injector (9) corrected.

12. Control unit (15) for an internal combustion engine (1), in particular a direct-injection internal combustion engine, which can inject a combustion chamber (4) into the fuel in a first operating mode during a compression phase and in a second operating mode during an intake phase via a high-pressure injection valve (9) and with a controller for cylinder equation at least in the first operating mode, the control device (15) being provided for switching between the operating modes, characterized in that the control device (15) for correcting torque errors (M_f_ik) of the individual cylinders (i ) necessary injection correction factors (r_ik) in several

Operating points (k) are determined and stored, a static flow rate error (q_stat) and a dynamic flow rate error (q_dyn) of the high-pressure injection valve (9) are determined from the injection correction factors (r_ik) and the fuel quantity to be injected into the combustion chamber (4) as a function of the determined flow rate errors ( q_stat, q_dyn) of the high pressure injection valve (9) corrected.